A common rule that has been applied both by individual investors and financial planners/brokers is the 4% rule. What is it? Basically, if you try to plan your retirement, you should expect to be able to retire 4% of your capital in the first year. Then, you can increase the amount that you withdraw every year to account for inflation.
One of the main differences between retiring with a traditional savings portfolio and a dividend portfolio one is that the ultimate goal is to be able to live off of the dividends and hopefully avoid selling any of the stocks. In such a way, there is very little to worry about in terms of outliving your expenses but it also means being able to leave a significant amount behind when that moment comes. I think those benefits are very significant.